Fix Maven spotlessApply aborting on first file with lints

[mirkoalicastro]

In spotless:apply, the Mojo throws an exception on the first file that had unsuppressed lints. This made it exit the loop, so:

• Remaining files were never formatted in that run
• Only the first file's lints were reported, hiding the rest

This diverged from the Gradle plugin that processes all the files and reports an aggregated failure.

This PR aligns the behaviour of the Maven plugin with the Gradle one.